[clug] NFSv4 "Invalid argument"

[George at Clug]

    HI,

I am unable to understand how NFS works with user permissions.  Does
anyone have experience with NFS shares in Debian Wheezy and could
explain to me how to manage user permissions for an NFS share ? Maybe
it is not even needed?

I searched the Internet but did not find anything useful, I did find
mentions of libnss-mysql and nfs4_disable_idmapping but I could not
find any detail on how this related to Debian.

# umount 192.168.0.12:/mnt/vg2/vol1/san12_nfs_ds1/kvm-images/images

# mount -t nfs  -v
192.168.0.12:/mnt/vg2/vol1/san12_nfs_ds1/kvm-images/images
/var/lib/libvirt/images
mount.nfs: timeout set for Mon Oct 13 20:42:13 2014
mount.nfs: trying text-based options
'vers=4,addr=192.168.0.12,clientaddr=192.168.0.137'

# chown root:root
/var/lib/libvirt/images/ISO/debian-7.5.0-amd64-DVD-1.iso 
chown: changing ownership of
`/var/lib/libvirt/images/ISO/debian-7.5.0-amd64-DVD-1.iso': Invalid
argument

# ls -al /var/lib/libvirt/images/ISO
total 11143136
drwxr-sr-x 2 nobody nogroup       4096 Oct 11 08:50 .
drwx--s--x 3 nobody nogroup       4096 Oct 11 09:45 ..
-rw-r--r-- 1 nobody nogroup 3938795520 Oct 11 08:49
debian-7.5.0-amd64-DVD-1.iso

I also tried the following;
# umount 192.168.0.12:/mnt/vg2/vol1/san12_nfs_ds1/kvm-images/images

# mount -t nfs -o
auto,noatime,nolock,bg,nfsvers=3,intr,tcp,actimeo=1800  -v
192.168.0.12:/mnt/vg2/vol1/san12_nfs_ds1/kvm-images/images
/var/lib/libvirt/images
mount.nfs: trying text-based options
'nolock,bg,nfsvers=3,intr,tcp,actimeo=1800,addr=192.168.0.12'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 192.168.0.12 prog 100003 vers 3 prot TCP port 2049
mount.nfs: prog 100005, trying vers=3, prot=6
mount.nfs: trying 192.168.0.12 prog 100005 vers 3 prot TCP port 33224

# chown root:root
/var/lib/libvirt/images/ISO/debian-7.5.0-amd64-DVD-1.iso chown:
changing ownership of
`/var/lib/libvirt/images/ISO/debian-7.5.0-amd64-DVD-1.iso': Operation
not permitted